preterm labor new

Preterm labor Osama M Warda MD Professor of OBS/GYN – Mansoura University

7-Mar-16 O Warda

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Definition WHO 2015

•  Preterm is defined as babies born alive before 37 weeks of pregnancy are completed. There are sub-categories of preterm birth, based on gestational age:

•  extremely preterm (<28 weeks) •  very preterm (28 to <32 weeks) •  moderate to late preterm (32 to <37 weeks). •  Induction or caesarean birth should not be planned before

39 completed weeks unless medically indicated.

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Key facts (Fact sheet N°363/WHO)

•  Every year, an estimated 15 million babies are born

preterm (before 37 completed weeks of gestation), and this number is rising.

•  Preterm birth complications are the leading cause of death among children under 5 years of age, responsible for nearly 1 million deaths in 2013.

•  Three-quarters of them could be saved with current, cost-effective interventions.

•  Across 184 countries, the rate of preterm birth ranges from 5% to 18% of babies born.

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INCIDENCE

•  Total incidence = 6-10%of all pregnancies

Ø  Spontaneous = 40-50% Ø  PROM= 25-40% Ø Obstetrically indicated = 20-25%

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Complications of preterm birth

Most of mortality and morbidity are experienced by babies born before34 weeks gestation

Major neonatal risks include: 1- Death 2- Respiratory distress syndrome 3- Hypothermia 4- Hypoglycaemia 5- Necrotising enterocolitis 6- Jaundice 7- Infection 8- Retinopathy of prematurity

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Risk factors for preterm labor

While the exact cause of preterm labor is often unknown, there is strong evidence that intrauterine infection may play a role in very early preterm labor.

Bacterial vaginosis increased the risk of preterm delivery >2-fold . Risks were higher for those screened (at <16 weeks) than those (at <20 weeks of gestation ).

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Risk factors for preterm labor, cont.,

Other risk factors include: 1.  Multiple pregnancy: risk >50% 2.  Previous preterm delivery: risk 20- 40% 3.  Cigarette smoking: risk 20-30% 4.  Cervical incompetence 5.  Uterine abnormalities 6.  Young age of mother - less than 16 years 7.  Lower socioeconomic status. 8.  Reduced body mass index (BMI<19kg/m2) 9.  Antiphosphlipid syndrome. 10.  Obstetric complications, including PIH, APHge, infection,

polyhydramnios, foetal abnormalities.

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Prediction of preterm labor

1.  Assessment of risk factors 2.  Vaginal examination to assess the cervical

status 3.  Ultrasound visualization of cervical

length and dilatation 4.  Detection of fetal fibronectin in cervico-

vaginal secretions

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• Digital examination is the traditional method used to detect cervical maturation, but quantifying these changes is often difficult.

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•  Vaginal ultrasonography allows a more objective approach to examination of the cervix.

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Prediction of preterm labor; (cont.)

- Fetal fibronectin (TrophoblastGlue): Promotes cellular adhesion at uterine-placental and decidual-fetal membrane interfaces

-ve FFN >>> > Negative predictive value of 99% (good –ve)

+ve FFN >>>> Positive predictive value of 13-30% 99.5% of symptomatic women with negative FFN are undelivered at 7 days 99.2% of symptomatic women with negative FFN are undelivered at 14 days

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Prevention of preterm labor

• Women at increased risk of preterm delivery may be identified by various risk factors in the obstetric history and treated accordingly.

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Supplemental progesterone: •  Progesterone im injection (100 mg amp) •  17 hydroxy progesterone im depot form •  Vaginal progesterone pessaries & creams •  Oral micronized progesterone or dydrogesterone - Start 2nd trimester, continue until 36 weeks if prior delivery before 34 wks - 17OHP use in high risk women reduced PTB by 15-70%

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•  QUIT SMOKING

•  Just say NO! (especially to cocaine)

•  Cervical cerclage (for cvx insufficiency)

•  Diagnose & treat infection •  Asymptomatic bacteriuria, BV, GC, chlamydia

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Diagnosis of preterm labor

3 criteria to document PTL(20-37w): 1-Regular uterine contractions occur at 4/20

min. or 8/60 min. Plus: progressive change in the cervix. 2- Cervical dilatation > 1 cm 3- Cervical Effacement ±80%.

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Diagnosis of preterm labor; CONT;

Suspected preterm labor with no cervical changes :

Negative FFN { + } Cervical length > 30 mm

The likelihood of delivering in the next week is less

than 1%. Thus most women with a negative test can safely be

sent home without treatment.

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Treatment of preterm labor

•  Tocolysis – inhibit myometrial contractility •  Magnesium salt •  Terbutaline (beta agonist) •  Indomethacine (PG synthetase inhibitor) •  Nifedipine (calcium channel blocker) •  Atosiban ( oxytocin receptor inhibitor)

•  Contraindications to tocolysis: •  IUFD, lethal fetal anomalies, NRFHT•  Severe IUGR, chorioamnionitis, antepartum hage.•  Severe pre-/eclampsia

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MgSO4

Terbutaline

Indocin

Nifedipine

Class �-agonist Cox inhibitors CCB

Action Competes for Ca

� cAMP � intracellular

Ca

� PGD production

Block Ca influx

Side Effect Pulm edema, ? � ped M&M

Tachy, �BP, palp, �K,

pulm edema

N/V, gastritis, narrowing of

DA, oligo

�BP, reflex tachy, ? � of

blood flow

Efficacy Not very good!

No � of PTB @ 7 days, sx

relief

Appears to be more effective than placebo

� # of women giving

birth at 7 days

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Green-top guidelines (1b): tocolysis for women in preterm labor

•  There is no clear evidence that tocolytic drugs improve outcome and therefore, it is reasonable not to use them. However, tocolysis should be considered if few days gained would be put to good use, such as completing a course of corticosteroids or in utero transfer. [A]

•  Use of tocolysisis not associated with a clear reduction in perinatal or neonatal mortality, or neonatal morbidity. [A]

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- Tocolytic drugs should be used in: 1-women with suspected preterm labor with otherwise uncomplicated pregnancy. [B] 2- women with preterm labor needing transfer to hospital that provide neonatal intensive care, or those who have no yet completed a full course of corticosteroids [✔]

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- Effectiveness of tocolytic drugs: •  Nifedipine and atosiban have comparable effectiveness

in delaying birth for up to 7 days.[A] •  Compared with beta- agonists, nifedipine is associated

with improvement in neonatal outcome, although there are no long-term data. [A]

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- Adverse effects of tocolytic drugs :-  Beta-agonists have a high ferquency of adverse

effects. Nifedipine, atosiban and COX inhibitors have fewer types of adverse effects. [A]

-  Using multiple tocolytic drugs appears to be associated with a higher risk of adverse effects and so should be avoided . [B]

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Recommended doses regimen for nifedipine & atosiban:•  Nifedipine; initial oral dose of 20mg followed by 10-20mg (three or

four times daily), adjusted according to uterine activity for up to 48 hours. A total dose > 60mg is associated with 3-4 fold increase in adverse effects. [✔]

•  Atosiban; an initial bolus dose of 6.75mg over 1 minute, followed by infusion of 18mg/hour for 3 hours , then 6mg/hour for up to 45 hours (to maximum of 330 mg) [✔]

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Glucocorticoids rule!

Why? •  Reduce the risk of neonatal RDS, IVH, NEC, and

mortality by 50% (FIFTY!) •  Benefit observed 18 hours after 1st dose, max benefit

@ 48 hours •  previously we used to give to GA 34W or less,

nowadays, GTG recommend them up to 39 weeks

How? •  Enhance maturation of lung architecture •  Induce lung enzymes resulting in biochemical

maturation

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Cervical cerclage

•  For cervical insufficiency which complicates 0.1-2% of all pregnancies and is responsible for 20% of late 2nd trimester losses.

•  Prophylactic cerclage – 12-14wks •  Rescue cerclage – when cervical changes already detected

-  Various techniques; shirodkar, MacDonald, Caspi, and Abdominal cerclage

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Cervical Cerclage: (GTG60 )

•  All decisions about cerclage are difficult and should be made with senior involvement. A doctor with the necessary skills and expertise to perform cerclage should carry out the procedure. [✔]

•  TYPES (definitions): cerclage terminology according to indication:

-  History –indicated cerclage at (12-14 weeks) -  Ultrasound -indicated cerclage at (14-24weeks) inserted as a

salvage measure in case of premature cervical dilation with exposed fetal membranes in vagina.

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Thank you 7-Mar-16 O Warda

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preterm labor new

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